Among thin-type image display elements, a plasma display panel (hereinafter simply referred to as a panel) has become practical as a large-screen display device from the advantage of high-speed display performance and easy upsizing.
A panel is formed of a front plate and a back plate attached with each other. The front plate has a glass substrate, display electrode pairs of scan electrodes and sustain electrodes disposed on the glass substrate, a dielectric layer formed so as to cover the display electrode pairs, and a protective layer disposed on the dielectric layer. The protective layer not only protects the dielectric layer from ion collision but also promotes generation of a discharge.
The back plate has a glass substrate, data electrodes formed on the glass substrate, a dielectric layer that covers the data electrodes, barrier ribs formed on the dielectric layer, and phosphor layers that emit light in red, green, and blue. The front plate and the back plate are oppositely disposed in a manner that the display electrode pairs and the data electrodes cross each other via a discharge space. The two plates are sealed at the peripheries with low-melting glass. The discharge space is filled with discharge gas including xenon. Discharge cells are formed at positions where the display electrode pairs face the data electrodes.
With a panel structured above, a plasma display device generates a gas discharge selectively in each discharge cell of the panel. Ultraviolet light generated at the discharge excites phosphors to emit light in red, green, and blue. Color image display is thus attained.
In a typical method for driving a panel, one field period is divided into a plurality of subfields, which is known as a subfield method. According to the subfield method, gradation display is attained by combination of the subfields to be lit. Each subfield has an initializing period, an address period and a sustain period. In the initializing period, a voltage is applied to the scan electrodes and the sustain electrodes to generate an initializing discharge. The initializing discharge generates wall charge on each electrode, which is necessary for an address operation in the subsequent address period. In the address period, scan pulses are sequentially applied to the scan electrodes, at the same time, address pulses are applied selectively to the data electrodes to generate an address discharge and to form wall charge. In the sustain period, sustain pulses are applied alternately to the display electrode pairs to generate a sustain discharge selectively in a discharge cell, by which the phosphor layers disposed in the discharge cells emit light for image display.
For obtaining higher quality of image, light-emitting control in discharge cells, i.e., which cells should be lit and which cells should not be lit, has to be done with reliability. That is, address operations should be properly completed within a predetermined period. To address above, manufacturers have been working on the development of a panel driven at a high-speed and seeking of improved driving method and driving circuits for providing high quality image so as to get best performance from the panel.
Discharge characteristics of a panel largely depend on the characteristics of a protective layer. In particular, the performance of electron emission and charge retention greatly affect the high-speed driving of a panel. To improve above, many studies on the material, structure, and manufacturing method for the protective layer have been made. For example, Patent Literature 1 discloses a plasma display panel with improvements in the panel and the electrode driving circuit. According to the disclosure, the panel has a magnesium oxide layer that exhibits a cathode luminescence emission peak at 200 to 300 nm. The magnesium oxide layer is generated through gas-phase oxidation of magnesium vapor. Besides, according to the electrode driving circuit above, scan pulses are sequentially applied to one of the display electrode pairs that constitute entire display lines, and at the same time, address pulses suitable for the display lines that undergo the application of scan pulses are applied to the data electrodes.
Recently, in addition to upsizing the screen, there has been growing demand for a high-definition plasma display device, such as a high-definition plasma display device with 1920 pixels×1080 lines and an extremely high-definition plasma display device with increased lines, for example, 2160 lines or 4320 lines; meanwhile, a sufficient number of subfields is necessary for smooth gradation display. Such a demanding situation requires the period for address operations per line to be further shortened. To complete address operations with reliability in a limited period, manufacturers are searching for an advanced panel with more reliable address operations at higher speed than before, a driving method thereof, and a plasma display device with driving circuits controllable the panel and suitable for the method.                [Patent Literature 1]Unexamined Japanese Patent Publication No. 2006-54158        